Instead writing out rambling sentences I’m just going to state some facts and what’s going on. Any help or direction would save any hair left in my head.
-1999 Trans Am
-I bought it used in 2002 with 41,xxx miles (Second owner)
-Drove it 2 months, engine messed up and I parked it in my garage until September of 2020. So it sat for 18 years, in a garage, with a car cover, it was taken care of while in there. No mice living in it or eating wires, etc.
-September 2020 I pull it out, have the engine rebuilt and everything else needed for a car sitting that long.
-I drove it roughly 1200 miles until July 2021.
-While I was out driving, the car started to miss or hesitate. When I would give it gas it would barely go, jump, not do anything and then start going. And then it got to a point where it would start, run for 10 seconds, and die. Then not start again for a day.
-I put my cheap code reader on it, even though it didn’t set any codes, and it said the crankshaft sensor had a problem. So I changed it, with a cheap Amazon one (I didn’t know at the time to use AC/Delco, etc). And after I changed it I DID NOT do a crank relearn.
-This didn’t fix the problem.
-Next after searching through fuel system and checking it thoroughly, it was ruled out.
-Swapped out the ECM to check it with another 99 T/A and it didn’t fix it.
-Finally found the wires running to the crankshaft sensor, starter, where melted. They were up against the header down low. These wires were fixed and the car started and ran fine.

-Now here is my new problem
-Car starts, drives and runs, but it will occasionally cut out, or loss engine power.
-For example, I have a 6 speed and coming out of a turn, when releasing the clutch and starting to give it gas, it’s almost like the pedal is doing nothing, it’s not getting a response. And then it comes right back and push the gas pedal and it’s fine. While cruising at any speed, it will just cut out, like a misfire almost, come right back and keep going like nothing is wrong. It may do it 2 times in 1 mile and not do it again for 5-10 miles.
-From what I read it was like a bad crankshaft sensor. I realized I put the cheap one in originally so replaced it with the AC/Delco and DID NOT do a crank relearn again. It didn’t fix the problem.
-I have been chasing this for 4 months and need some help


So Here’s my questions. Any help would greatly be appreciated.
1.Could my BCM have anything to do with this? That’s where the mechanic is telling me to look.
2. Could not doing the crank relearn make it keep cutting out until that’s done?
3. Could throttle sensor make it cut out while driving?

 

I would continue to check for bad wiring, connectors/connections, and all grounds.
The intermittent nature tells me connection(s) are breaking/reconnecting.

 

This, since you had a set of wires melt on you and cause a severe short, there's a good possibility that there are other shorts that you have not found yet. It's a PIA I used to run schematics decades ago when dealing with generators but usually your bad short will lead to more because the computer is trying to compensate for the original.

 

Thanks for the reply’s guys.
I should pull that groups of wires back off, completely strip all tape and wire loom and visually check first?
I’m guessing checking continuity with a voltage meter after?
The wires going into the crank sensor plug also didn’t seem real tight and “secure”, so I was going to order a new one and solder it in.

 

Definitely strip the tape off if there's tape on them. Visually check and always check for continuity. You never know if there's a broken wire inside the plastic jacket. After that use connection spray to make sure everything is clean and plug everything back in nice and tight. Make sure the boots are in good shape and are not old and worn causing the connection to be lose thus causing play between your female/male connectors. Good luck

 

thank you. I will try this and see what happens.

 

Was the engine rebuilt to Oem specs, or did you change cam events, compression, injectors, etc? The lack of pedal response sounds to me like a lean issue that’s occurring at only certain rpm’s/areas of the fuel trims. Have you had the car tuned?

 

Engine was rebuilt back almost to oem. Basically cam only engine. Car has been tuned. It was at a shop for a couple of months. I messaged him after I noticed it still cutting out and they went through everything in the tune and said it was good. The went through the entire fuel system, checked all grounds, made sure injectors were flowing, etc. before they found the burnt wires.

 

Since this has the wires that originally melted and we’re repaired, I’m thinking I will just buy a new harness and eliminate any checking of the old wires. Found this and it would be easier to just replace in my opinion. Anyone know of a reason this wouldn’t be a good idea?

 

Definitely a good idea it will cut your down time and no need to trouble shoot that wiring harness. You will.also have new connectors, boots and a warranty. Win win win 🤘🏽

 

To expand on the above, it might be wise to replace any harness or wiring that is subject to excess heat/chafing/scraping or other such abuse, especially if those wires are quite old and embrittled. Playing it safe with wiring is always the best course of action.

 

Without data, gonna be lots of trial and error. Scan PCM for any codes. If none, record/datalog to see what's going on when the problem occurs. If you suspect ignition issue, you could do a wiggle test on wires/harness that you suspect a problem with. If you suspect fuel, you could drive with pressure gauge on fuel system taped to windshield.

 

awesome. Thanks for the reply

 

absolutely, especially with the car sitting for 18 years. Gonna have some bugs to work out.

 

no codes yet, but I’m waiting for hp tuners to arrive, should be here Tuesday, and I will get it logged and see what comes up when that’s happening. Going to try this wiring harness and then if that doesn’t work, probably start with ignition. Fuel system was completely gone through and cleaned out, So I’m not suspecting that. But you never know. Going to get the wiring harness today and will try it out. I will keep you guys posted.

 

Bench test all the sensors. I've gotten TPS, CPS, IAT, Oil pressure sensors all DOA ...

 

dang, really? Thanks. I’m not the best with electrical. Should I just check continuity between each connector and the pin at the other end? Thanks again for the heads up

 

You'll have to google each one like
"Bench test TPS Chevy 5.3"
They are often different, some are just a ohm measurement some need power ground then test the output.. etc..
Service manual will tell as well.

The ECu will throw a code on a sensor that's just totally bad "usually" but for instance a TPS with a bad spot in it may not show a code..

Good Luck!

 

thanks so much for the help guys. I’ll let you know how to harness goes

 

What cam? What is a basically Cam only engine?, I think it still could be your tune to be honest